The Blacksmith is easy. Find the old crone selling wares near the Bonfire in the Forest of Fallen Giants' castle. She'll sell you a key to the smithy in Majula. Return to the smithy, unlock the door, talk to the smith outside, and the shop will soon open.

Titanite is harder to come by. You'll mostly find it in chests scattered around the world. It's not the most exciting discovery, but since many upgraded simple weapons outperform fancy ones, it's an important one.